1. Field of the Invention
The present invention relates to bearing preload tools, and more particularly to a bearing preload tool for differential assembly for motor vehicles, and a method for using thereof.
2. Description of the Prior Art
Differentials for automotive or similar uses are well known in the prior art, and generally comprise a differential case rotatably mounted in a differential housing or differential carrier by axially spaced differential bearing assemblies. The differential bearings are typically preloaded to provide the desired amount of backlash between a drive pinion and the ring gear of the drive gear assembly or to eliminate end play of the rotor have presented problems, particularly as the bearing assemblies or gears wear. Proper engagement of the ring gear carried by the differential case with the input drive pinion is necessary, and subsequent wear of the gears or bearings will result in misadjustment of backlash and possibly end play in the rotor. This in turn normally requires adjustment of the bearings. Generally, prior art differential case bearings have been made adjustable by use of adjustment shims or the like, with it many times being necessary to remove the differential case from the differential housing, select shims having appropriate thickness, then reassemble the differential case to affect adjustment of backlash or bearing preload. The selection of the shims is, currently, practically guesswork, and depends on a workmen""s experience. Typically, it requires several disassembling-reassembling operations before the correct bearing preload is achieved. Such labor-intensive procedures add cost and complexity to the adjustment procedure.
Thus, there is a need for a tool that is simple and inexpensive that would allow reducing time for selecting shims of appropriate thickness for properly preloading differential bearings in accordance with manufacturer""s specifications.
The present invention provides a novel universal differential bearing preload tool and a method for using thereof for mounting a differential case in a differential housing with a predetermined bearing preload,
In one preferred embodiment, the universal differential bearing preload tool includes a pair of opposite cylindrical discs simulating differential bearing cups, a disc spreading device for adjusting a distance between the discs for simulating a bearing preload, and a force measuring device associated with said disc spreading device. The opposite cylindrical discs are removably fastened to the preload tool, and may be selected from a plurality of discs having assorted external diameters simulating differential bearing cups of different sizes and manufacturers.
The bearing preload tool is used in a method for mounting a differential case in a differential housing providing a predetermined bearing preload. The method comprises the steps of placing a bearing preload tool into the differential housing by spreading the discs until the discs are snug fit against a bearing bores, then measuring a first distance between certain base points on the differential housing in a non-preloaded condition. Next, the discs are spread outwardly until a desired preload force is achieved. A second distance between the base points in a preloaded condition that defines a desired spread is measured, and bearing preload tool is removed from the differential housing. Then, the bearing preload shim is selected based on a difference between the first and second distances, and a differential case along with the shim is mounted in the differential housing through differential support bearings.
Therefore, the present invention provides a novel universal bearing preload tool and method for mounting the differential assembly in the differential housing using the universal bearing preload tool with a predetermined bearing preload, which is simple, cost effective, and substantially reduces time and labor expenses.